Grid coupling seal and method

ABSTRACT

A system and method for replacing a sealing arrangement of a grid coupling without removing or disturbing a mechanical connection of the coupling with driver and driven shafts connected to the coupling includes providing combined seal members having gasket seal portions that are integrally formed with radial seal portions and that are disposed between portions of the housing and the rotating seal group of the grid coupling.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims priority tocommonly owned and U.S. Application No. 16/026,281, filed on Jul. 3,2018, the contents of which are incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

This patent disclosure relates generally to grid couplings and, moreparticularly, to seals for grid coupling split covers.

BACKGROUND OF THE INVENTION

Grid couplings are a known type of coupling used in applications such asrock and aggregate conveyors where both high torque levels and dampingrequirements are desired. Unlike other known coupling types, for examplegear and disc couplings, grid couplings are uniquely configured toreduce vibration by as much as 30%, and to cushion shock loads, whichprotects and extends the life of driving and driven power transmissionequipment.

A typical grid coupling includes two hubs, each having a series ofteeth, which are installed in opposing relation. A grid spring elementis meshed between the teeth to mechanically interconnect the two hubs. Acover, hereafter referred to as housing, is disposed around the gridspring to protect against contamination by debris and to enclose alubricant that is used to lubricate the interfaces between the gridspring and the teeth.

One of the biggest, if not the biggest, limitation of grid couplings istheir limited ability to accommodate misalignment. While great atdamping vibration, grid couplings are not especially well configured tooperate in the presence of parallel shaft misalignment that is more thana minimal angle, for example, about 0.5 degrees. Additionally, gridcouplings require periodic cleaning and reapplication of lubrication,and replacement of seals and housing gaskets, which typically requiresdisassembly of the coupling and a laborious process to realign thecoupling during reinstallation. For example, radial or O-ring sealsdisposed to seal a neck of each hub to the housing require removal ofthe hub for installation insofar as the seal is not sufficiently largeto stretch over the teeth of the hub, which may also cut or otherwisedamage the new seal during installation, and must be installed from theexternal end of the hub relative to the coupling. Reinstallation of thehubs onto the rotating shafts requires a careful realignment such thatthe parallel and angular shaft misalignment is within specifications,and is an especially time consuming process when a heated interferencefit is used to couple the hubs onto the rotatable shafts.

SUMMARY OF THE INVENTION

The disclosure describes, in one aspect, a grid coupling. The gridcoupling includes two housing halves that are connectable to one anotherto form a housing having an internal cavity, and an opening disposed ateach of a first axial end and a second axial end of the housing. Arotating group is at least partially disposed within the internal cavityand has two hubs rotatably engaged by a spring element to rotate about arotational axis. Each of the two hubs has a cylindrical bearing surfacethat extends axially along at least a portion of each of the two hubsand along the rotational axis such that, when the grid coupling isassembled, the cylindrical bearing surface extends through the openingdisposed at each of the first axial end and the second axial end. Therotating group is adapted for mechanical connection between a drivershaft and a driven shaft to transfer rotational motion between thedriver and driven shafts.

In one embodiment, each of the two housing halves is generally saddleshaped and includes two flanges that are coplanar along a plane thatextends parallel to the rotational axis from the first axial end to thesecond axial end. The two housing halves are connected to form thehousing at the two flanges. Each of the two housing halves furtherincludes a channel disposed at each of the first axial end and thesecond axial end, the channel extending peripherally around the openingat each of the first axial end and the second axial end, the channelbeing oriented perpendicularly to the rotational axis.

The grid coupling further includes two combined seal members, each ofthe two combined seal members comprising at least one gasket sealportion, and at least one radial seal portion. When the grid coupling isassembled, each of the two combined seal members is configured to beinserted around the rotating group while the rotating group remainsconnected between the driver and driven shafts and the housing isremoved, such that, when the two housing halves are assembled around therotating group and the two combined seal members, the internal cavity issealed by at least one gasket seal portion from one of the two combinedseals is disposed in sealing relation between two opposed flanges, andthe at least one radial seal portion is disposed in the channel insealing and sliding relation between the channel and the cylindricalbearing surface.

In another aspect, the disclosure describes a combined seal member forforming a seal between a rotating group and two housing halves of a gridcoupling. The combined seal member includes a gasket seal portion, whichis flat and extends along a plane that is parallel to a rotational axisof the grid coupling. The gasket seal portion is configured to provide amechanical face seal between opposing flanges formed on the two housinghalves. The gasket seal portion has an inner end, which is closer to therotational axis than an outer end, and first and second axial ends. Thecombined seal member further includes two radial seal portions, eachhaving a U-shape and being connected at one end to the first or secondaxial ends of the gasket seal portion. The two radial seal portionsextend in parallel to one another and along respective planes that areperpendicular to the rotational axis. When the grid coupling isassembled, the gasket seal portion is disposed between the opposingflanges of the two housing halves, and the two radial seal portions aredisposed in sealing and sliding relation between a housing andcylindrical bearing surfaces of the rotating group.

In yet another aspect, the disclosure describes a method for replacingseals in a grid coupling. The method includes providing a grid couplingin an assembled position between two rotating machine components. Whilea rotating group of the grid coupling remains connected between therotating machine components, the method further includes removing ahousing from around the rotating group of the grid coupling, removingexisting seals of the grid coupling disposed between the rotating groupand the housing, inserting two seal elements around the rotating group,each of the two seal elements including a gasket portion and two radialseal portions, and assembling the housing around the rotating group andthe two seal elements such that the two radial seal portions aredisposed in sliding and sealing relation between the housing and therotating group and the gasket portion creates a mechanical face sealbetween flanges of two halves of the housing. The method also includessecuring the two halves of the housing together to form the housing.

In one embodiment, the method for replacing seals in a grid couplingincludes providing a second gasket portion in each of the two sealelements. The second gasket portion creates a mechanical face sealbetween the flanges.

In one embodiment, the method for replacing seals in a grid couplingincludes inserting each of the two radial seal portions into acorresponding channel formed around at least a portion of an opening ofthe housing that surrounds a cylindrical bearing surface of the rotatinggroup.

In one embodiment, the method for replacing seals in a grid couplingincludes compressing a thicker cross section of the gasket portion alongan inner end of the housing and a thinner cross section of the gasketpotion along an outer end of the housing.

In one embodiment, each gasket portion is flat and includes first andsecond axial ends, and each radial seal portion has a U-shape connectedat one end to the first or second axial ends of a respective gasketportion. The two radial seal portions extend in parallel to one another.

In one embodiment, each gasket portion sealably engages the flanges ofone of the two housing halves, and each radial seal portion has asemicircular shape. Each of the two seal elements is formed as anintegral structure from an elastomeric material.

In one embodiment, each radial seal portion has a cross sectional shapethat is flat on an outer periphery and convex on an inner peripherythereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a grid coupling in accordance with thedisclosure.

FIG. 2 is an exploded view of two housing halves for a grid coupling inaccordance with the disclosure.

FIG. 3 is an isometric view of a grid spring element for a grid couplingin accordance with the disclosure.

FIG. 4 is an isometric view of a hub for a grid coupling in accordancewith the disclosure.

FIG. 5 is an isometric view of an inner group assembly for a gridcoupling in accordance with the disclosure.

FIG. 6 is an isometric view of the inner group assembly of FIG. 5 withseals installed thereon in accordance with the disclosure.

FIG. 7 is an isometric view of the seals shown in FIG. 6 but removedfrom the grid coupling for illustration.

FIG. 8 is an isometric view of a seal in accordance with the disclosure.

FIG. 9 is a sectional view of the seal of FIG. 8.

FIG. 10 is a flowchart fora method of replacing seals in a gridcoupling.

DETAILED DESCRIPTION OF THE INVENTION

This disclosure relates to mechanical couplings and, more specifically,to grid couplings such as the couplings used to transfer rotationalmotion in an industrial process, for example, a conveyor system. Knowngrid couplings typically include two hubs that are interconnected by aresilient or spring element. Relative motion of the hubs, especiallywhen transferring impact or sudden loads, can be damped by the resilientor spring element that connects the couplings. During operation, rubbingand friction within the coupling, which can be detrimental to theoperation and longevity of the coupling, can be alleviated by cleanuseable lubricant. Any damage to the seal or gasket during installationcan jeopardize the life of the lubricant and therefore the life of thecoupling. To maintain the lubricant in place within the coupling, and toavoid contamination of the working surfaces and components of thecoupling, a housing encloses the moving parts of the coupling. Thehousings belong in two major varieties, which are horizontally andvertically separating housings. In the present disclosure, the exemplaryembodiment shows a horizontally separating housing arrangement, i.e., ahousing that separates along a plane that is parallel to the rotationalaxis of the coupling, but it should be appreciated that the devices andmethods described herein may be applicable to vertically separatinghousings as well, i.e., housings in which the plane of separationbetween two housing halves is perpendicular to the rotation axis of thecoupling.

An exploded view of a coupling 100 in accordance with the disclosure isshown in FIG. 1 to reveal the main components thereof. These maincomponents are also shown removed from the coupling in FIGS. 2-5. Inreference to these figures, the coupling 100 includes a rotating group102 that is made up from two hubs 104 that are connected by a spring 106in the typical fashion. The spring 106 shown in the illustratedembodiment is illustrative and not limiting to the various types ofsprings that can be used in grid couplings, for example, springs havingtapered or straight cross sections and the like. The rotating group 102has two cylindrical bearing surfaces 108, one on each hub 104, whichgenerally slidably and sealably engage a housing made from two housinghalves 110. During operation, inertia effects between the rotating group102 and the housing 110, as well as relative motion between portions ofthe rotating group 102, may cause sliding between the housing and thebearing surfaces 108.

Each hub 104, as is also shown in FIGS. 4 and 5, includes an axleportion 402 that has a generally cylindrical shape and may includefeatures such as a central opening (not shown), keyways or key slots(not shown) or other structures that permit a mechanical connection ofthe hub to other rotating machine components. The axle portion 402 isconnected to a flange 404, which extends radially outwardly with respectto an outer diameter of the axle portion 402 and which is disposedtowards an inner end of the hub 104 in its orientation relative to thecoupling.

The flange 404 includes a series of teeth 406 that are separated byslots 408 arranged in alternating fashion around the entire outerperiphery of the flange 404. When the rotating group is assembled, asshown in FIG. 5, axially extending portions 302 of the spring 106 aredisposed within the slots 408. The axially extending portions 302 areconnected by bent portions 304. One of the bend portions includes a slitor opening 306, which permits the spring 106 to open for assembly aroundthe flanges 404 of two hubs that, together, make up the rotating group102.

Turning now to the housing, each of the two housing halves 110 has agenerally C-shaped cross sectional shape such that, when the two halvesare connected, a hollow cylindrical housing is assembled around thecenter of the rotating group 102. Sealing of an interior portion of thehousing is accomplished by two combined seal members 112. Each combinedseal member 112 is arranged to provide a face seal at some portions, anda radial seal at other portions, as described below.

More specifically, and in further reference to FIG. 6, each seal member112 includes two gasket portions 114 disposed at either end of each sealmember. In one embodiment, it is contemplated that a single gasketportion 114 can also be used. When the coupling 100 is assembled, eachgasket portion 114 is disposed to create a face seal along a surface 602between two mating gasket portions 114 from two seal members 112assembled around the rotating group 102. Along their outer-facingsurfaces 604, each gasket portion is arranged to matingly engage aflange 116 (FIG. 2) of the respective housing half 110. Each gasketportion 114 further includes two openings 117, which accommodatefasteners (not shown) that connect the two housing halves 110 to oneanother.

Each seal member 112 further includes two U-shaped radial seal portions118 disposed at either axial end of the member relative to a rotationaxis 120 of the coupling 100. The radial seal portions 118 areconfigured to fit within channels 122 that extend peripherally aroundhalf-circle openings 124 disposed at each axial end of each of the twohousing halves 110. When disposed within the channels 122 of anassembled housing 110 around the rotating group 102, the radial sealportions 118 slidably and sealably engage the bearing surfaces 108 tocreate a radial seal. This radial seal, along with the face sealsprovided by the gasket portions 114, and the remaining radial seals,provide a complete seal around an internal cavity 126 of the housingthat contains the spring 106 and surrounding structures of the hubs 104,which are typically also lubricated.

The two seal members 112 in mating relation are shown removed from thecoupling 100 in FIG. 7. FIGS. 8 and 9 show a seal member 112 and a crosssection thereof. In reference to these figures, it can be seen that thetwo seal members 112 are in direct contact with one another along thegasket portions 114, which seal against each other along the surface602, and also along radial contact surfaces 702 (four total) formedbetween the blunt or exposed diametrically opposite ends 902 (FIG. 9) ofthe radial seal portions 118. In an embodiment where a single gasketportion 114 is used per seal member 112, a single layer gasket canprovide the face seal between the mating housing flanges 116.

To ensure that a proper seal is created both around the bearing surfaces108 of the rotating group 102, between the flanges 116 of the housinghalves 110, and also at the transition or junction areas 802 (FIG. 8)between the gasket portions 114 and the radial seal portions 118,additional material may be provided in certain areas or sections of theseal members 112. More specifically, the seal members 112 may be madeprimarily from an elastomeric material, which possesses a desiredresilience and resistance to temperature, debris and chemicals, as thosemight be encountered during service in any environment. One possiblematerial is rubber, while others include fluoro-elastomers such asViton®, which may further have lubrication coatings deposited thereon.For comparison, known sealing arrangements for grid couplings of thistype include gaskets made from cardboard and rubber O-ring seals thatrequire disassembly of the hubs from the respective axles they areconnected to during assembly of the coupling. In one embodiment, thegasket portions 114 are made by over-molding an elastomeric layer 804 onone or both sides of a grid structure or substrate 806, as shown in theenlarged detailed section of FIG. 9. In another embodiment, the sealmembers 112 may be bonded or over-molded directly onto the housinghalves 110.

Returning now to the gasket portions 114, the area of the surface 602,which is radially inward, and which also includes the blunt ends 902along an inner end of the flange, is made to be thicker than thecorresponding area of the surface 602 that is radially outward along anouter end of the flange. In this way, additional sealing material isprovided to help compress the blunt ends 902 and improve their sealing,and also to help seal the junction area 802, which in previous designsof grid couplings has been prone to leakage of lubricant form theinternal cavity 126 and provides a path for egress of debris oraggregate into the internal cavity 126.

In the illustration of FIG. 8, it can be seen that an outer thickness ofthe gasket 114, which is denoted as d, is smaller than an innerthickness, which is denoted as D, by a small amount, which isexaggerated in the illustrations, of about 1 or 2 thousandths of an inch(0.02-0.05 mm). Regarding the cross sectional shape of the radial sealportions 118, as shown in FIG. 9, they include a rounded rectangularshape having an outer periphery 904 that is flat, to provide acylindrical outer face, and two radially extending faces 906 that arealso flat, to provide two annularly shaped surfaces. Together, the outerperiphery 904 and radially extending faces 906 engage the walls of thechannels 122 (FIG. 2). An inner periphery 908 is curved in a convexdirection to provide a smaller contact area and, thus, a higher contactor seal pressure, with the bearing surfaces 108 (FIG. 5) of the rotatinggroup 102. The shape of the cross section for the radial seal portionscan also be selected depending on the particular application, which mayalso cause a corresponding change in the shape of the channels formed inthe housing. For example, the cross section of the radial seal portioncan take on a circular cross section, similar to an O-ring, or anothershape such as an “X” cross section, similar to quad ring seals, whichcan provide additional or redundant radial seal interfaces with thecylindrical bearing surfaces of the rotating group.

A flowchart for a method of replacing seals in a grid coupling is shownin FIG. 10. The method includes providing a coupling in its assembledposition between two rotating machine components at 1002. While therotating group of the grid coupling remains connected between therotating machine components, the housing is removed at 1004 and two sealelements disposed between the housing halves. Each of the two sealelements includes a gasket portion disposed between flanges of thehousing halves, and two radial seal portions disposed around openings atthe ends of the housing between the housing and bearing surfaces of therotating group. Following service at 1006, which may include addition oflubricant while the two hubs of the rotating group remain connectedbetween the rotating machine components, the same or different two sealelements are reassembled around the rotating group at 1008, and thehousing halves are assembled around the rotating group at 1010 such thatthe seal members are disposed between the two housing halves 110, whichare secured to one another at 1012 to form a housing around the rotatinggroup. In certain embodiments, the reassembly steps can be carried outin any desired order. For example, in one alternative embodiment, theseal elements may be first installed onto the housing halves, and thenthe housing halves, with the seals installed thereon. may be wrappedaround the rotating group of the coupling to complete the assembly. Suchalternative embodiment may be especially useful when the seals have beenbonded onto, or have been molded directly onto, portions of the housinghalves.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

What is claimed is: A method for replacing seals in a grid coupling,comprising: providing a grid coupling in an assembled position betweentwo rotating machine components; while a rotating group of the gridcoupling remains connected between the rotating machine components:removing a housing from around the rotating group of the grid coupling;removing existing seals of the grid coupling disposed between therotating group and the housing; inserting two seal elements around therotating group, each of the two seal elements including a gasket portionand two radial seal portions; assembling the housing around the rotatinggroup and the two seal elements such that the two radial seal portionsare disposed in sliding and sealing relation between the housing and therotating group and the gasket portion creates a mechanical face sealbetween flanges of two halves of the housing; and securing the twohalves of the housing together to form the housing.
 2. The method ofclaim 1, further comprising providing a second gasket portion in each ofthe two seal elements, the second gasket portion creating a mechanicalface seal between the flanges.
 3. The method of claim 1, furthercomprising inserting each of the two radial seal portions into acorresponding channel formed around at least a portion of an opening ofthe housing that surrounds a cylindrical bearing surface of the rotatinggroup.
 4. The method of claim 1, further comprising compressing athicker cross section of the gasket portion along an inner end of thehousing and a thinner cross section of the gasket portion along an outerend of the housing.
 5. The method of claim 1, wherein each gasketportion is flat and includes first and second axial ends and whereineach radial seal portion has a U-shape connected at one end to the firstor second axial ends of a respective gasket portion, wherein the tworadial seal portions extend in parallel to one another.
 6. The method ofclaim 1, wherein each gasket portion sealably engages the flanges of oneof the two housing halves, and each radial seal portion has asemicircular shape, and wherein each of the two seal elements is formedas an integral structure from an elastomeric material.
 7. The method ofclaim 1, wherein each radial seal portion has a cross sectional shapethat is flat on an outer periphery and convex on an inner peripherythereof.